Internal combustion engines convert chemical energy in a fuel to mechanical energy. As part of the conversion, the fuel can be combusted, thus causing hot combustion products to expand within the engine. The expansion of the combustion products can be used to move mechanical components of the engine, such as pistons. Combustion reactions can have several products, or emissions, some of which can be undesirable. For example, when hydrocarbons are used as fuel, combustion products can include HC, CO, CO2 and NOx.
In an attempt to reduce emissions, efforts have been made to utilize substantially carbon-free hydrogen as a combustion fuel instead of hydrocarbons. When hydrogen (H2) is used as the fuel, there is not a substantial amount of HC, CO, or CO2 emissions, because the fuel does not include carbon that can be turned into HC, CO, or CO2. Therefore, hydrogen fuel is currently viewed as a good fuel choice for environmentally clean engines.
The inventor herein has recognized that it can be difficult to achieve a desired air-to-fuel ratio when hydrogen is used as a combustion fuel. In particular, it can be difficult to introduce enough air into the cylinder relative to the amount of fuel in the cylinder. Unlike more conventional liquid fuels, hydrogen gas can occupy a significant volume within a cylinder, thus limiting the volume available for air at a given pressure.
Others have attempted to address this problem by using direct cylinder fuel injection so that a full charge of air can be introduced to a cylinder and effectively trapped within the cylinder before hydrogen is injected. In this manner, the cylinder contains a full charge of air, and the injected hydrogen simply increases the pressure within the cylinder. Thus far, direct hydrogen fuel injectors have evolved from existing injectors designed to inject other fuels, such as natural gas or propane.
The inventor herein has recognized that the design and material selection for various components in hydrogen fuel injectors are inadequate for hydrogen fuel applications. Using such injectors, it is believed that internal failures such as seizing, galling, and leakage can cause rough running and misfiring in as little as five hours of operation. As an example, the bearings that are used to align the pintle in more conventional fuel injectors may not be adequately lubricated in a hydrogen fuel injector because the gaseous fuel does not lubricate the bearings in the same manner a liquid fuel lubricates the bearings. The bearings can wear prematurely due to a lack of lubrication, thus causing pintle misalignments, which in turn can cause the tip of the pintle to prematurely wear. This can cause undesired leaks.
At least some of the issues associated with hydrogen fuel injection may be addressed by a fuel injector including a cantilever support for aligning the pintle with the fuel injector nozzle. In this manner, pintle alignment and sealing capacity can be improved and/or prolonged.